Detecting devices are demanded for detecting explosives in order to prevent terrorism and maintain security in the midst of the aggravated international conflicts. Baggage inspection apparatus using X-ray transmission are now widely used as detecting devices chiefly in airports. Since the X-ray detecting device detects objects as lumps and identifies dangerous materials from information of shape, it is called bulk detection. The detecting method based on gas analysis is called trace detection, and used to identify substances from chemical analysis information. The trace detection is characterized in that very small amounts of ingredients attached to a baggage or the like can be detected. A security scanner of greater precision is desired to produce by combining bulk detection and trace detection in order to socially strengthen the security.
Custom offices also use detecting devices in order to detect forbidden chemicals sneaked through various routes. Although bulk detectors and drug-sniffing dogs are chiefly used in custom offices, a trace analyzer for forbidden chemicals is eagerly desired to produce in place of the drug-sniffing dogs.
Various analyzing methods such as ion mobility spectroscopy and gas chromatography have been tried as trace detection. Research is being conducted for developing apparatus having high speed, high sensitivity and high selectivity as important factors in the detecting device.
In these situations, a detecting method based on mass spectrometry is proposed that is fundamentally excellent in speed, sensitivity and selectivity as, for example, disclosed in JP-A-7-134970. A conventional detecting device based on mass spectrometry will be described with reference to FIG. 16.
An air suction probe 1 is connected through an insulation pipe 2 to an ion source 3. The ion source 3 is connected through an exhaust port 4 and an insulation pipe 5 to an air exhaust pump 6. The ion source 3 has a needle electrode 7, a first aperture electrode 8, an intermediate pressure portion 9 and a second aperture electrode 10. The needle electrode 7 is connected to a power source 11, and the first aperture electrode 8 and second aperture electrode 10 are connected to an ion accelerating power source 12. The intermediate pressure portion 9 is connected through an exhaust port 13 to a vacuum pump. An electrostatic lens 14 is disposed in the stage succeeding the intermediate pressure portion. A mass spectrometric portion 15 and a detector 16 are disposed in the stage succeeding the electrostatic lens 14. A detected signal from the detector 16 is supplied through an amplifier 17 to a data processor 18. The data processor 18 detects a plurality of m/z values (mass number of ion/valence of ion) of particular chemicals, thus deciding if the detected gas contains a particular chemical.
This data processor 18 has a mass determining section 101, a drug-A determining section 102, a drug-B determining section 103, a drug-C determining section 104 and an alarm driving section 105. An alarm display 19 that is driven by the alarm driving section 105 has display portions 106, 107, 108 disposed.